The present invention relates to a magnetic recording/reproducing memory including magnetoresistance elements which use the magnetization reversal or magnetic reversal technique using spin-transfer torque and in which magnetization-reversal is caused with a unidirectional current.
Currently in the field of memories represented by the dynamic random access memory (DRAM), research and development of universal memories which satisfy requirements of fast speed, high integration and low power consumption and which has a feature of non-volatility are being conducted worldwide. The magnetic random access memory (MRAM) is highly expected as a candidate for the universal memory.
The MRAM has a structure obtained by arranging tunnel magnetoresistance (TMR) elements in an array form. The TMR element is based on a structure having an insulation layer sandwiched between two ferromagnetic layers, the insulation layer being used as a tunnel barrier. The TMR effect is an effect in which the resistance of the TMR element changes greatly depending upon whether the magnetization directions of the two ferromagnetic materials are parallel or anti-parallel with each other. In 1990's, TMR elements using aluminum oxide in the insulation layer have been researched. In the case where magnesium oxide which has attracted attention in recent years is used in the insulation layer, a resistance change rate as large as 500% is reported. They are described in, for example, Luc Thomas, Masamitsu Hayashi, Xin Jiang, Rai Moriya, Charles Rettner, and Stuart S. P. Parkin, “Oscillatory dependence of current-driven magnetic domain wall motion on current pulse length”, Nature 443, 197 (2006) (non-patent document 1). In addition, according to Luc Thomas, Masamitsu Hayashi, Xin Jiang, Rai Moriya, Charles Rettner, and Stuart Parkin, “Resonant Amplification of Magnetic Domain-Wall Motion by a Train of Current Pulses”, Science 315, 1553 (2007) (non-patent document 2), writing with a current using magnetization reversal caused by the spin-transfer torque at the time of writing is also verified at an array level.